About ninety percent of all automobile accidents are utlimately caused by the driver's actions himself. Furthermore, about forty percent of known auto accidents are rear-end collisions. The determination of the proper following distance behind another vehicle is therefore a critical factor in minimizing such accidents. There are many suggestions as to the appropriate stopping distance for a given speed. The "rule of thumb" of leaving one car length for every ten miles of speed has long been proven inadequate. The proper stopping distance is much greater for faster speeds and additional safety factors must be added for diverse road and weather conditions. It therefore becomes a difficult problem to know whether at a given speed there is sufficient distance between your vehicle and another vehicle. The determination of the proper distance is an ever changing requirement of normal driving.
In the aforementioned parent application there is described a vehicle safety device which gives a visual indication to a driver of one vehicle concerning the safety of the distance between his vehicle and another vehicle based upon the speed at which he is driving. The device therein described includes a housing having an illumination source and a screen impervious to light. The screen contains a plurality of pairs of windows. The windows constituting a pair are separated from each other by a spacing which depends upon the resolving power of the eye. For a predetermined speed, the windows constituting a particular pair are separated such that at distances between the vehicles, up to a predetermined minimum safe stopping distance, the windows constituting that pair are seen as two windows indicating an unsafe condition; for distances between the vehicles which are greater than the minimum stopping distance by a fixed amount, the two windows appear as one, indicating a safe condition; and for distances therebetween, a hazy condition appears which then indicates that caution must be exercised at that speed for the distance between the vehicles.
The warning device of the aforementioned patent application is based upon the optical phenomena that two illuminated objects spaced from each other will tend to merge as the viewer moves away from the two illuminated objects. A number of embodiments of this concept were presented in the aforementioned parent application. The present application provides a variation on that concept. However, in the present application only a single warning area need be provided for a particular speed. Additionally, the present invention utilizes the optical principle that objects tend to become smaller and disappear as the distance between the viewer and the objects increases. When the distance is reduced, the objects will again reappear.
It is intended that all of the material disclosed in the earlier parent application is herein incorporated by reference.
It is, accordingly, an object of the present invention to provide a visual collision avoidance warning device which gives an easily observable indication of whether a vehicles is at a safe, unsafe, or caution needed distance from another vehicle for the speed at which it is traveling.
It is another object of this invention to supply an auto driver with a visual means of keeping his vehicle in a safety zone in relation to the constantly changing traffic situations surrounding him.
A further object of this invention is to provide a reliable distance-gauging device applicable to all driving conditions.